1. Field of the Invention
This invention relates to silicone elastomer compositions, the process of producing them, and the cured product.
2. Description of the Prior Art
Low viscosity silicone elastomer compositions have been used as mold-making materials, potting and encapsulating materials, and injection molding materials. A low viscosity is useful in such applications as it allows the composition to easily coat the surfaces against which it is placed and to flow into extremely small spaces. When using low viscosity polymers, it is difficult to obtain physical strength properties of the desired levels due to the low molecular weight of the polymers.
A method of increasing the molecular weight of a hydroxyl endblocked polydiorganosiloxane has been disclosed by Crossan and Toporcer in U.S. Pat. No. 4,020,044, issued Apr. 26, 1977. They disclose that mixing a silane of the formula ##STR1## with a hydroxyl endblocked polydiorganosiloxane will yield a higher molecular weight material that will have vinyl functionality distributed along the chain which can be used for further reactions, such as curing reactions. They teach that when this material and a hydroxyl endblocked polydiorganosiloxane are mixed together, the mixture reacts very rapidly with the reaction going to completion at room temperature in a short period of time. Such a mixture would have a short shelf life after mixing and would be unsuitable for use in applications where it is necessary for the mixture to be a low viscosity during the placement and forming operations before cure. Such a mixture would be unsatisfactory in an operation such as impregnating a large electrical coil where the viscosity must be low to allow the material to flow between all the wires and where the working time must be long enough to allow complete impregnation of the entire coil before the viscosity rises to a significantly higher level.
A class of compounds of the formula ##STR2## is disclosed in U.S. Pat. No. 2,876,234, issued Mar. 3, 1959, by Hurwitz and deBenneville where R.degree. is a cyclohexyl group, aryl group, alkenyl group, or an alkyl group of 1 to 18 carbon atoms; Y is an alkylene group having 3 to 18 carbon atoms with a chain of at least 3 but no more than 5 carbon atoms extending between the N atom and the carbonyl group; and x is an integer having a value of 1 to 4. They teach the compounds may be pesticides. The compounds may be polymerized to produce fusible products which may be applied to leather, paper pulp, fabrics, or nonfibrous sheets and heated to produce an infusible condition.